In response to the trend of carbon reduction, the world actively promotes green energy industry. Since the global warming issue has not been solved and fossil energy is short in recent year, the development of renewable energy has currently become important in worldwide. Moreover, the related research and application in photovoltaic power is much popular in renewable energy.
On-grid photovoltaic power generation system can be divided into home use and commercial use, and the difference between them is power requirement. The common problems for those power generation systems are power disturbances such as natural disasters (lightning strikes, saline damage) and foreign objects touch. Those power disturbances lead to the power generation system instability so as to cause voltage dip in the grid. Therefore, the overall power generation system is very likely to fail and results in inconvenience for the user terminals. For a user terminal as a large-scale production line, the failure of the power generation system will shut down the production line so as to severely damage the users. In order to overcome the impact of voltage dip, several countries in the world are stipulating power grid rules for low voltage ride through (LVRT) capability. When the voltage dip occurs, the power generation terminal can provide a certain reactive power to the grid until the grid returns to normal in order to prevent power generation loss caused by the separation between the power generation terminal and the user terminal due to voltage dip.
Generally, during the power generating, the power generation system will sent the electricity to the grid through a two-stage voltage conversion mode, which means that the power generating terminal will perform DC/DC voltage conversion in a first boost stage, and then the boosted DC voltage from the first boost stage is inputted to the DC/AC converter in a second boost stage. However, the two boost stages not only consume energy but also increase the size and cost of the power generation system due to the adding of the voltage converters.
Accordingly, the present invention will provide a novel solution for the problems mentioned above.